A conventional string/shoelace securing device is shown in FIGS. 10 to 13, and generally includes a base 61, two positioning pins 62, a spool 63, a ring 64, a cap 65 and a wire or shoelace. The base 61 includes a connection plate 611 which is fixed to a shoe (not shown) and the spool 63 is rotatably mounted to the central post on the base 61. A bolt 612 extends through the central post from the underside of the base 61 and is connected to the post 653 on the underside of the cap 65. The two positioning pins 62 are cooperated with two springs 622 and inserted into reception holes in the base 61 and each positioning pin 62 has an inclined surface 621 on a top thereof. The ring 64 is mounted on the spool 63 to position the spool 63 which further includes first teeth 631 which are engaged with second teeth 651 defined in the underside of the cap 65. The underside of the cover 5 further includes third teeth 652 which are cooperated with the inclined surfaces 621 to allow the cap 65 to rotate one direction to rotate the spool 63. The shoelace 66 extends through the skirt of the base 61 and wraps the spool 63, two ends of the shoelace 66 are fixed to the spool 63. When tightening the shoelace 66, the user simply rotates the cap 65 to rotate the spool 63 to fasten the shoelace 66. When releasing the shoelace 66, the cap 65 is pulled away from the base 61 to disengage the first teeth 631 from the second teeth 651, and the third teeth 652 from the inclined surfaces 621, the shoelace 66 can be pulled and loosened.
Another conventional string/shoelace securing device is shown in FIGS. 14 and 15, and generally includes a base 71 having first teeth 711 defined in a top thereof, a spool 72 having second teeth 721, a spring 74, a cap 73 which is rotatably mounted to the base 71 by a bolt 75. The spool 72 is located between the base 71 and the cap 73 and the second teeth 721 are engaged with third teeth 731 defined in the underside of the cap 73. The cap 73 further includes four flexible arms 732 located at the underside thereof and each arm 732 has one end fixed to the cap 73 and the other end is a free end which has a claw 733 which is removably engaged with the first teeth 711. By rotating the cap 73, the spool 72 is and rotated to tighten the shoelace. By lifting the cap 73, the shoelace can be loosened.
For the first conventional shoelace securing device, the two positioning pins 62 are positioned by the ring 64 and the positioning pins 62 compress the springs 622. This arrangement makes the two positioning pins 62 do not compress the springs 622 evenly which pushes the positioning pins 62 by different forces such that the rotation of the cap 65 may not be smooth as desired. Besides, the installation of the springs 622 into the reception holes requires time. Furthermore, because the bolt 612 extends from the underside of the base 61 to connect the cap 65, so that the whole set of the device has to be separated when a part between the base 61 and the cap 65 needs to be replaced.
For the second conventional shoelace securing device, because the arms 732 has one end fixed to the cap 73 so that the force reacts from the first teeth 711 has to be transfer a distance to the end that is fixed to the cap 73. This may result in uneven biasing forces to the arms 732 and may have the same problem as the first conventional securing device.
The present invention intends to provide an improved securing device for tightening string, strap, or shoelace, wherein the spool is pushed straightly and upward to cooperate with the cap, the forces between the cap and the spool are even so that the operation of the cap is more reliable and smooth.